John Chang, MD
NPI 1265594527 · Gastroenterology Physician · San Diego, CA
Enrolled with Medicare as Practitioner - Gastroenterology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
John Chang, MD is a Gastroenterology Physician provider in San Diego, CA (NPI 1265594527).
Provider details
- NPI number
- 1265594527
- Entity type
- Individual
- Primary specialty
- Gastroenterology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- A110350 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
19 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
354 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
Medicare volume is ranked against active providers in the same specialty. Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our .
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Biopsy of Large Bowel Using a Flexible Endoscope45380 | 126 | $71 |
| Removal of Polyps Or Growths of Large Bowel Using an Endoscope With Mechanical Snare45385 | 117 | $256 |
| Biopsy of Esophagus, Stomach, And/Or Upper Small Bowel Using a Flexible Endoscope43239 | 50 | $99 |
| Moderate Sedation Services Provided By the Same Physician Or Other Qualified Health Care Professional Performing a Gastrointestinal Endoscopic Service That Sedation Supports, Requiring the Presence of an Independent Trained Observer to Assist in the MonitoG0500 | 33 | $5 |
| Colorectal Cancer Screening; Colonoscopy on Individual Not Meeting Criteria for High RiskG0121 | 15 |
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 5 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Sodium, Potassium,mag Sulfatesbrand: Sod Sulf-Potass Sulf-Mag Sulf | 124 | 123 |
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Gavilyte-G | 71 | 70 |
| Peg3350/Sod Sulf,bicarb,cl/Kclbrand: Peg-3350 and Electrolytes | 44 | 42 |
| Omeprazole | 27 | 19 |
| Peg3350/Sod Sul/Nacl/Kcl/Asb/Cbrand: Peg3350-Sod Sul-Nacl-Kcl-Asb-C | 14 | 14 |
Medicare Part D only. These counts cover prescriptions paid through Medicare Part D in 2024 — they do notinclude cash-pay, commercial-insurance, Medicaid, or Part B–administered drugs, and badly undercount high cash-pay categories (e.g. GLP-1 weight-loss, testosterone, and ED medications). Any drug with 10 or fewer claims is omitted by CMS, and beneficiary counts under 11 are suppressed — so a missing drug means , never zero. This is a factual claims summary, not an endorsement, not medical advice, and not a consumer report. Source: CMS Medicare Part D Prescribers — by Provider and Drug.
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$6,942 across 10 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-12-14
- Last updated
- 2023-08-21
- Certified
- 2023-08-21
Frequently asked questions
- What is John Chang's NPI number?
- John Chang's National Provider Identifier (NPI) is 1265594527, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is John Chang's specialty?
- John Chang is listed in the NPPES registry with a primary specialty of Gastroenterology Physician (Allopathic & Osteopathic Physicians).
- Where is John Chang located?
- John Chang's practice location on file with NPPES is 200 W Arbor Dr, San Diego, CA 92103-9000.
- What is John Chang's phone number?
- The practice phone number listed in the NPPES registry for John Chang is (800) 926-8273.
- Does John Chang accept Medicare?
- John Chang is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is John Chang's NPI active?
- Yes — John Chang's NPI (1265594527) is active in the NPPES registry as of the last update on 2023-08-21.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.